Intercooler theory and sizing debate (1 Viewer)

[Christian]

Hi all

I have searched the web and asked around. I need some info on this in regards to a 1KZ-T conversion.

There's a lot of info on intercooling gasser's but very little on intercooling diesels.
Some just project gasser theory and practice on to diesels, some say that is a big mistake.
I have searched, on Yotatech, Toyotadiesel and the web in general and found one article that expalins the difference in diesel intercooling vs. gas-powered intercooling.
I others want to read the article it's here:
Browser Warning

A brief summary:

Turboed gas engines are only on boost for short periods. There are several rewasons for this, the fact that a diesel does not close off the air supply when you lift your foot of the throttle, diesels being pushed harder from the factory and running higher boosts in general.

This means that a gas engine (on boost occasionally) uses the intercooler as a heat-sink. The aluminium absorbs the heat on boost, and dissipates it to ambient air, as weel as intake air when not on boost.

Diesels are on boost more of the time. Therefore a diesel intercooler must be more efficient at dissipating heat to ambient air.
Conclusion from the article: " [...] However, because more boost is used much more often, intercooling a diesel turbo requires much better design than an equivalently sized petrol turbo engine." (Browser Warning)


If you want more detail, read the article, it is quite informative!

Well we are installing a 1KZ-T from a prado in an old army Volvo truck.
The 1KZ-T has no intercooler from the factory. I want to add one for a few reasons listed in order of importance:

1. The 1KZ-T has a reputation for cracking heads. This is usually because the engine runs too hot, adding an intercooler might help.
2. Keeping engine bay temps down. the Volvo being a cab forward design, there's a possible heat build-up under the cab where the engine sits. adding an intercooler might help that.
3. Getting a few more ponys...

But I have no idea of what size to get?

I have found two options that might fit, but this is where I would like the experts to come in; short way, better flow or long way through, better cooling?


Overall Size 23"x11"(9.5")"x3"
Core Size 19.5"X6"X3", 2.5" Inlet & Outlet

Overall Size: 29"x8"x3.5"​

2.5" Inlet & Outlet One Side
3.5" Core​

​

​

​

​

​

Core Size: 22"X8"X3.5"​

So I thought it would be interesting to start a thread on the subject, not only for my application, but for all applications. It could be nice if w could gather the knowledge here instead of having a lot of fragmented info all over.

 

[Dougal]

I don't think I'd use either of those. Instead I'd be looking for one the same dimensions as the lower one, but with an outlet/inlet on each side. The BMW one shown at the top of that autospeed article shows exactly what I mean.

The first type you show will not flow evenly across all the cores, the second one has a silly long flow path for no real benefit.

Lastly, fit the biggest intercooler you can. A bigger and thinner intercooler will cool much better than a smaller and thicker one.

 

[R2HKS]

I think you also need to look at the type of intercooling ie air to air vs water to air and also what you do with your truck. If its just for the highway then a front mount air to air intercooler would be fine. However if you say drive it on the beach in really soft sand in 2nd gear low range then you aren't going fast enough for a front mount IC to do anything at all. That's where water to air comes into its own.

You also need to look at the pressure drop across the core, how much the IC cools the intake air and the possible lag created from long and large intercooler piping.

More questions than answers at this stage.

 

[Christian]

Thanks for the replys!

The thing is I'm really restricted size-wise. I'm installing the complete driveline of a KZJ70 in this:


And since ithe intercooler has to sit in front af the radiator there are some size restrictions, and the outlet/inlet has to be on the same side.

But my thought is that the original coolers mounted under the bonnet of the 90 series, which have the same engine, are quite small.

I get the idea of fitting the biggest one you can, since turbo-lag because of intercooler volume has very little to no effect on a diesel.

Water-to-air is a path I won't take. We are building an expedition type vehicle, and there's more risk involved in a water-to-air setup than in air-to-air.
The point about 2nd gear and sand is true, but the electric fan will help there I hope!

Both coolers were found on Ebay and have cfm specs:

Long path:
Compress Air Flow Rate<600Cubic Feet/Min, Rated to 400-500 Max HPWorking Pressure:35~40PSIPressure Drop2~5psi@35psi; 0.2~0.5psi@15psiHot Air Temperature32°F~302°F (0°C~150°C)

Short path:
Compress Air Flow Rate<700Cubic Feet/Min, Rated to 400-500 Max HPWorking Pressure:35~40PSIPressure Drop1~3psi@35psi; 0.2~0.5psi@15psiHot Air Temperature32°F~302°F (0°C~150°C)

I have no idea how dependable these figures are though...

What I would like was if somebody could give some kind of "rule of thumb" on the matter.

 

[R2HKS]

And since ithe intercooler has to sit in front af the radiator there are some size restrictions, and the outlet/inlet has to be on the same side.

What about using an air to air sitting on the roof with a scoop?

 

[Christian]

What about using an air to air sitting on the roof with a scoop?

Good idea, but were thats where the bed goes

here's what we have planned:

 

[Dougal]

Good idea, but were thats where the bed goes

here's what we have planned:
View attachment 325183

Is a 1KZ going to be enough for that?

 

[Christian]

Well, i thought a lot about that. The original engine is the Volvo B30 gas engine, 115hp... And it still managed more than 100 km/h.

We plan to have a total weight of 3.5 tons and it is not a race car, but an expedition vehicle, so we need reliability and milage rather than hp...

I had thought about bigger Toyota 6-cylinder engines, but there's not a lot of room and weight would be an issue.

 

[Dougal]

Well, i thought a lot about that. The original engine is the Volvo B30 gas engine, 115hp... And it still managed more than 100 km/h.

We plan to have a total weight of 3.5 tons and it is not a race car, but an expedition vehicle, so we need reliability and milage rather than hp...

I had thought about bigger Toyota 6-cylinder engines, but there's not a lot of room and weight would be an issue.

The 1KZ's crack heads in 2 ton vehicles which push about 1/3 of the air yours will. I'd be worried about longevity. Especially if you've got an earlier motor, after 2000 I haven't heard of any cracking.

I'd be looking for a 3-4 ton truck engine for that. Not necessary a light 4wd engine.

 

[Christian]

Well the engine and gearbox sits on the floor in the shop. It's from a 1996 KZJ70. So thats what it'll be!
I have though about longevity and headcracking. That is one of the reasons I want to put an intercooler on it. Maybe we will crack the head, but then we'll have a newer one on it!

"I'd be looking for a 3-4 ton truck engine for that. Not necessary a light 4wd engine."

The 1KZ-T is used in the Dyna's and they haul up to 3,5 tons here, including a trailer it might be up to 7 tons!

The Volvo has a factory axle and hub gearings at 7.1:1 So it won't be a fast runner. A popular conversion is using a merc OM613 engine, that's even smaller than the 1KZ-T...

Look at Merc Sprinters, Ford Transits, Iveco's ect. we have here in Europe. None of those have engines with a displacement more than 3 liters.

 

[Dougal]

The 1KZ-T is used in the Dyna's and they haul up to 3,5 tons here, including a trailer it might be up to 7 tons!

The Volvo has a factory axle and hub gearings at 7.1:1 So it won't be a fast runner. A popular conversion is using a merc OM613 engine, that's even smaller than the 1KZ-T...

Look at Merc Sprinters, Ford Transits, Iveco's ect. we have here in Europe. None of those have engines with a displacement more than 3 liters.

As long as you know what you're up for. I rate the ford, mercedes etc engines more highly than a 1KZ. For a start they're all direct injection and have stronger heads. The 96 models are well known for head issues so I hope you've got an easy way to get it back out.

I haven't seen a dyna with a 1KZ, the dyna's I've checked all had B series engines. We do have hiace vans with 1KZ"s but they were detuned compared to even the non-intercooled hilux. The prados and surf's got the highest power outputs in the vehicles I've seen.

 

[Christian]

i understand your concern, and it is highly appriciated, don't get me wrong. And I am not sure what we're (my girlfriend and me) are in for, this is uncharted territory.

The reason we haven't picked a newer commonrail or direct injected engine is because we value simplicity and parts availiability in an expedition type vehicle. Toyota diesel parts are by far the easiest to come by all over the world. Besides commonrail and DI engines are much more sensible when it comes to cleanliness of fuel. The 1KZ can be run on pure wo.

Another reason for choosing this engine is regulations here. you are not allowed to change engine and put one in that is more than 20 % bigger than original.

Some have put the Nissan 2,8 Patrol in the Volvo's and they are very satisfied!

 

[Christian]

- But back on the intercooler track. Does anyone know a "tuning kit" for the 1K-T with a bigger intercooler?

Dougal, you critized the one with the long path, having read the article referred to in the first post I agree with you, but after having looked at Merc Sprinter intercoolers I have noticed that they are very long and thin, why would mercedes do that if it is such a bad idea? I'm not in anyway saying you're wrong, but I would like to understand "how it all works..."

 

[lshobie]

I know it's not what you want to hear, but I think that instead of figuring out what intercooler to use you should be thinking about carrying an extra head or engine with you. That engine is too small for that truck.

You also said that you don't want a water/air intercooler because you are worried about the possibility of it leaking and ruining the engine, but if you aren't worried about cracking the head or blowing the engine then why would you worry about a leaking intercooler???

If I had no other option then I would atleast use an water/air intercooler because you are going to get very little airflow over an air/air type with the front of that truck the way it is, and ptutting something in front of the rad that will cause the engine to run even hotter is as bad a move as puting that engine in there in the first place. And, with an air/air intercooler you will need air flowing over it for it to work - that will be hard with a truck that will be working its ass off just to hit 80kms/hr on a downhill stretch let alone trying to climb hills or mountains.

Just my opinion, but I think you are going to be kicking your own ass while sitting on the side of the road wondering how to fix that engine. Please post here while you are on your trip so we can see your progress.

Louis.

 

[Christian]

Wauw! that was one hell of a kidney punch!

But I know you say it all with the best of intentions Louis.

You have some valid points, I have read a lot of water/air intercooler debate on the net. Feeling that simplicity is king in a lot of cases I have opted for air. I must say that cost also figures...

Your worry about placing the engine under the cab is valid, but there's a lot more room and air than there is in a Hiace with the same engine. Bear in mind that this engine sits in the rear of Hino busses as well. In the Volvo more than half the engine is exposed beneath the cab.

We will give the engine, and especially the head a really good check-up, and take it on a test trip, putting it through it's paces, before any serious expeditioning.

And remember a 6 ton (13.200 lbs) Unimog 416 only has 100 hp

I feel it will be best if I outline the entire project and all the ideas and considerations made, so all of you can understand what we are doing.

The Truck

Well it's a Volvo TGB13 from the swedish army. Produced in 1975, like me. When we bought it, just after new year, it had 8,680 km's on the clock.
It has portal axles and it's a real 6x6 with diff locks all around. you can drive it in either 4x6 or 6x6 mode.
Originally it has a Volvo B30 engine with 117 hp (92 kW) at 4200 rpm and 206 Nm (151 lb/ft) of torque at 2500 rpm.

Despite these low figures the heaviest version has a GVWR of 5.7 tonnes or 12,566 lbs.

It has low/high and a four speed gearbox with a drive ratio in 4th of 1:1.

The axle ratio incl. portal hubs on ours is 7.1:1

Albeit these figures might not impress you, a Volvo C303 (the 4x4 version) won Paris Dakar in 1983.

Our Plan

We have taken the old box of the back of it. And this has reduced the weight by almost 1.2 tons.
As it sits now, a rolling truck with a bare frame behind the cab it weighs 2.1 tonnes (4,629 lbs). That's about the same as a HJ60.

The camperbox we plan on building will be a lot lighter than the original army ambulance box. The fiberglass alone wil weigh no more than 240 kgs.
We have set ourselves a GVWR restriction of 3.5 tonnes (7,716 lbs) because of regulations here.

We will use the Toyota R150F gearbow with a R452 fifth gear, thus getting a 1:0.7 ratio in fifth.

So if the engines are compaired, this is what it looks like:

B30
117 hp @ 4200
206 Nm (151 lb/ft)@2500
1KZ-T
125 hk @ 3600
295 nm(217 lb/ft)@2000

So hp-wise we are not gaining a lot, but torque-wise we are. I have driven this truck, on the way home when we bought it, more than 100 miles while it weighed 3.3 tonnes, and it still did 100 km/h.


We have chosen the 1KZ-T for a few reasons:

• It's relatively light
• Spare parts are availiable all over the world
• It's economic
• It has about the same hp as original, but more torque
• it's a LANDCRUISER!

Remember that this is not a racecar, it's being build to go out and enjoy the trip itself.


I hope this explanation gives you all a better understanding of the project.

 

[Dougal]

- But back on the intercooler track. Does anyone know a "tuning kit" for the 1K-T with a bigger intercooler?

Dougal, you critized the one with the long path, having read the article referred to in the first post I agree with you, but after having looked at Merc Sprinter intercoolers I have noticed that they are very long and thin, why would mercedes do that if it is such a bad idea? I'm not in anyway saying you're wrong, but I would like to understand "how it all works..."

A single pass long and thin intercooler is far better than a twin pass intercooler of the same shape.
For a start in your twin pass intercooler the inlet air is heating the outlet air. Secondly the airflow path is terrible.

My concerns on the 1KZ aren't based on the power or torque of the engine, they're based on the fragility of it.
The 96's are one of the earliest KZ's and they crack heads in a much lighter duty application than yours. If it were a 2003 engine I wouldn't be as concerned.
A cracked head in those is not a roadside fix, nor is it a repair you'd want someone to be attempting in a remote location with language barriers.
The 1KZ isn't a very economical engine either. I have two family members with later versions of that engine (hilux and prado), my 4wd is heavier, older, has more driveline drag, worse aerodynamics and a 33% bigger engine yet I get better fuel economy. My engine is a direct injection Isuzu made in 1985/6.

I would suggest a 13/14B or similar engine (14/15BT if you can find one) for that vehicle. Not for reasons of power, but reasons of durability and fuel economy.

If you were to stray from Toyota then an Isuzu 4BD1T or 4JB1T would be my pick.

 

[Christian]

A single pass long and thin intercooler is far better than a twin pass intercooler of the same shape.
For a start in your twin pass intercooler the inlet air is heating the outlet air. Secondly the airflow path is terrible..

Ahh! Of course! I get the point about the heat transfer, it's so simple I overlooked it.

My concerns on the 1KZ aren't based on the power or torque of the engine, they're based on the fragility of it.
The 96's are one of the earliest KZ's and they crack heads in a much lighter duty application than yours. If it were a 2003 engine I wouldn't be as concerned.

Well, I have heard and read good things about this engine. And I have driven it myself, first in a 90 series, later in a 70 series, and I really like the way it performs. There's room in the budget for a new head if it comes to that though, engine + gearbox+ transfer has cost us less than 350 $

A cracked head in those is not a roadside fix, nor is it a repair you'd want someone to be attempting in a remote location with language barriers.
The 1KZ isn't a very economical engine either. I have two family members with later versions of that engine (hilux and prado), my 4wd is heavier, older, has more driveline drag, worse aerodynamics and a 33% bigger engine yet I get better fuel economy. My engine is a direct injection Isuzu made in 1985/6.

I would suggest a 13/14B or similar engine (14/15BT if you can find one) for that vehicle. Not for reasons of power, but reasons of durability and fuel economy.

If you were to stray from Toyota then an Isuzu 4BD1T or 4JB1T would be my pick.

I prefer the 1KZ-T, especially in a cab-forward vehicle. It is a much quieter engine, balancing axles and stuff like that. And as I said, I like the way it drives. And, well...:


And:

 

[rchalmers3]

Hi Christian,

Looks like an exciting project! I have only a few general suggestions:

If I read your post correctly, you indicated that you are considering using an intercooler to control engine heat. I don't think an intercooler is going to affect the engine operating temperature, at least not directly. Please consider further the theory of an intercooler before embarking on any expenditures. Your greatest impact on maintaining engine cooling will be from the cooling system design.

You may want to reconsider your reluctance to using an air/water intercooler. With the air/water intercooler you will have greater flexibility in regards to the installation design. Given the vehicle configuration, I believe the rewards of mounting the cooler someplace other than in front of the radiator will be beneficial to your goals of total heat management.

My last suggestion is to do some comparison. That Volvo has very nice gearing in the portal axles that will provide excellent torque multiplication, thus multiplying the increased engine torque all that much more!!! My guess the increased frontal area of the planned design and additional weight are negated by the portal gearing, but you will have to perform the mathematical study to be sure.

Given the motor will not have to work as hard in the Volvo chassis as it did in the Toyota donor truck (at least at lower speeds), I think your project has a high probability of success!

Thanks for sharing the pics and warm regards on your project!

Rick

 

[Christian]

Hi Christian,

Looks like an exciting project! I have only a few general suggestions:

If I read your post correctly, you indicated that you are considering using an intercooler to control engine heat. I don't think an intercooler is going to affect the engine operating temperature, at least not directly. Please consider further the theory of an intercooler before embarking on any expenditures. Your greatest impact on maintaining engine cooling will be from the cooling system design.

Thanks!

According to several posts all over the web real world observation on EGT's show that an intercooler reduce EGT's by 1-200 degrees fahrenheit. We will focus heavily on engine cooling and for the moment have several options. one is an aftermarket aluminium radiator:

Another option is having a radiator custom build in copper/brass. The latter has the benefit that it can be fixed by soldering. it is nearly impossible to fix an aluminum radiator "on the road".

You may want to reconsider your reluctance to using an air/water intercooler. With the air/water intercooler you will have greater flexibility in regards to the installation design. Given the vehicle configuration, I believe the rewards of mounting the cooler someplace other than in front of the radiator will be beneficial to your goals of total heat management.

That is true. So we will look more in to it. However while the front of the truck may seem very compact, the tunnel where the radiator sits is almost 3 feet deep, before you reach the engine. So there is a lot of room actually.

My last suggestion is to do some comparison. That Volvo has very nice gearing in the portal axles that will provide excellent torque multiplication, thus multiplying the increased engine torque all that much more!!! My guess the increased frontal area of the planned design and additional weight are negated by the portal gearing, but you will have to perform the mathematical study to be sure.

Given the motor will not have to work as hard in the Volvo chassis as it did in the Toyota donor truck (at least at lower speeds), I think your project has a high probability of success!

Thanks for sharing the pics and warm regards on your project!

Rick

Thanks! I have done a lot of calculations on engine revs vs. speed. In fact that is one of the major issues when converting these Volvo's to diesel. There are availiable kits to convert to a Mercedes OM603 or OM606 engine. But a major issue is they retain the original gearbox. So the engine has to do high rev's to maintain road speed. That is one of the reasons we have chosen to discard the original Volvo gearbox and use the Toyota. We are actually planning to use the internals of the R150F paired with a 5th gear from a R452 thus geatting a 0.7:1 fifth gear.
With Michelin XZL 11/16 tires we will be doing 37 km/h at 1000 revs in fifth.

Thanks again, we have high hopes for it, but as i've already stated it has not been done before, not with this engine. Mercs, old Nissan 3.3's, even a 2H, but not this one!

 

[Dougal]

Thanks!

According to several posts all over the web real world observation on EGT's show that an intercooler reduce EGT's by 1-200 degrees fahrenheit. We will focus heavily on engine cooling and for the moment have several options. one is an aftermarket aluminium radiator:

Those guys reporting 1-200F EGT drop will be running higher boost than you are. I think those 1KZ without the intercooler only run about 10psi boost. There isn't enough heat in the intake for an intercooler to make that big a difference.

An intercooler is still a good thing to have.